"I still miss him very much and I still have the empty feeling," Joe told ET Canada.

Unfortunately, Joe (who divorced Cory's mother, Ann McGregor, in 1989) was excluded from his son's funeral. "I didn't get to go to his viewing, which would have meant a lot," he said.

Cory and brother Shaun fishing with their father, Joe

Courtesy Joe Monteith

However, "I did receive an email from his mother a couple of days ago [and] in the near future she's going to be sending me some of his stuff," Joe added.

Cory and Joe were estranged for much of their lives but had begun to rebuild their relationship a couple of years before Cory died. Still, the pair were not in contact at the time Cory went to rehab in March 2013. "The only thing I knew," Joe said, "was through watching [the news]."

Joe also spoke about Cory's costar and girlfriend at the time of his death, Lea Michele. (Michele, 27, is now dating aspiring actor and model Matthew Paetz.)

"She's a beautiful young woman, she's just getting to the top of her career and I don't expect her to go out and do it alone," Joe said. "She should enjoy life. She had a good time when she was with Cory, from what I understand, but life's gotta go on."

Despite Cory's addiction, his father remembers him as a "likable, approachable" man. "If he was in the room, you'd be smiling," he said.

Although a year has passed, Joe's distress over his son's death lingers. "He enjoyed life, that's why I was so shocked about the outcome of everything," he said. "He just seemed to enjoy life overall and then all of a sudden he's gone."